The present invention relates, in general, to electronics, and more particularly, to methods of forming semiconductor devices and structure.
In the past, the electronics industry utilized various methods and structures to produce multi-phase power supply systems. A typical multi-phase power supply system divided a load of the power supply system into several regions. The power supply controller was also divided into a number of channels or phases. In some cases, each phase was assigned to a particular region of the load. The different phases had a power switch to provide switching of the input power. A pulse width modulator (PWM) circuit provided a variable duty cycle PWM signal to control the switching for each phase. All of the phases were summed together to generate a single output voltage. One problem with the prior controllers was offset errors and inaccuracies in the components within the controllers. The ability to equally share the load current between the channels or phases was affected by these and other variations in the respective PWM circuits and switches. For example, different PWM comparators may have different offsets that affected the PWM duty cycles and the resulting load currents, variations in the values of passive components such as ramp capacitors often resulted in different ramp slopes, and the ramps often had different offsets. Such differences affected the load currents. Thus, each channel and the associated passive and active components had to be sized to carry the maximum current value instead of an average current value. Increasing the current carrying potential of each channel increased the size of the power transistors, associated drivers, passive components, and other portions of system thereby increasing the costs of the power supply system.
Accordingly, it is desirable to have a method of forming a multi-phase power supply system and power supply controller that more equally distributes the load current between each of the phases or channels, that reduces the cost of the switches, and that reduces the costs of the passive components of the system.
For simplicity and clarity of illustration, elements in the figures are not necessarily to scale, and the same reference numbers in different figures denote the same elements. Additionally, descriptions and details of well-known steps and elements are omitted for simplicity of the description. As used herein current carrying electrode means an element of a device that carries current through the device such as a source or a drain of an MOS transistor or an emitter or a collector of a bipolar transistor or a cathode or anode of a diode, and a control electrode means an element of the device that controls current through the device such as a gate of an MOS transistor or a base of a bipolar transistor. Although the devices are explained herein as certain N-channel or P-Channel devices, a person of ordinary skill in the art will appreciate that complementary devices are also possible in accordance with the present invention. It will be appreciated by those skilled in the art that the words during, while, and when as used herein are not exact terms that mean an action takes place instantly upon an initiating action but that there may be some small but reasonable delay between the reaction that is initiated by the initial action.